Out of 9,658 young women, less than one-third of those eligible to receive the human papillomavirus (HPV) vaccine chose to get it. And the majority of those women didn’t even complete the entire 3-dose regimen.

The most common sexually transmitted virus among US girls, HPV can cause cervical cancer – the second leading cause of cancer deaths among women worldwide, with nearly 4,000 deaths expected a year in the US alone. The vaccine was licensed in 2006 as the first that can prevent this type of cancer.

Tracy’s team looked at four years of clinical data on nearly 10,000 young women in the Baltimore area between the ages of 9 and 26. Only 27% started the vaccination process, and only 31% of them completed all 3 doses.

“What’s concerning is people starting and not completing the vaccine,” Tracy said. “If you think you are protected and you’re not... you might have a false sense of security.”

At any given moment, about a third of sexually active teenagers are infected with one of 40 HPV types, which can also lead to vaginal and vulvar cancers in females and genital warts in both sexes.

Currently, there are two vaccines available to women – Merck’s Gardasil and GlaxoSmithKline’s Cervarix – and the CDC recommends vaccinations for females ages 11 to 26. (Gardasil is also available to prevent genital warts in males.)

The year after Gardasil was licensed, a Merck spokesperson said the company based the price on a number of factors, especially the value it brings society: “HPV-related diseases cost the US healthcare system about $5 billion every year, and we took that into consideration.” Within a year of its approval, Merck sold more than 5 million doses, just enough to immunize about 5% of the recommended population. Projection data showed that vaccines would gross more than $11 billion if all women 11 to 26 in the US were vaccinated.

Tracy’s study didn’t look for reasons why women didn’t opt for the vaccine or finish the necessary doses, though she plans to conduct a small trial to see if sending text-message reminders from doctors would help.
Image: electron micrograph of human papillomavirus/NCI.

Janet Fang has written for Nature, Discover and the Point Reyes Light. She is currently a lab technician at Lamont-Doherty Earth Observatory. She holds degrees from the University of California, Berkeley and Columbia University. She is based in New York.
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